Creating Bullet Trail in Cycles
Its created by vector-displacing pixels in post-production. The game engine does this with pixel shaders in post-production too.
Check this its related: How to make a heat distortion effect?
You just don't need a particle simulation for the trail but a single texture behind the bullet will do.
This will create a spherical ball-like distorsion:

Smear it and adjust it in your favourite 2D application to create some water-like wave effect.

Red channel affects the X position
Green channel affects the Y position
Pixel value of 0.5 is no change, brighter is positive direction, darker is negative
Leave blue channel black

You can also sculpt the effect on a plane and bake it into a normal map. Then erase the blue channel from that map.